[func]Test with optimize_for_wide_provider_trees

Placement implemented a workaround optimization for large provider
trees. This patch enables that optimization to run the pci_in_placement
related nova functional tests with this config enabled.

Change-Id: I0b5e13673cb4cc7c57aeae50914ace443dfc18fa
Signed-off-by: Balazs Gibizer <gibi@redhat.com>

nova/tests/functional/integrated_helpers.py

@@ -1376,7 +1376,9 @@ class _IntegratedTestBase(test.TestCase, PlacementInstanceHelperMixin):
         if self.CAST_AS_CALL:
             self.useFixture(nova_fixtures.CastAsCallFixture(self))
 
-        self.placement = self.useFixture(func_fixtures.PlacementFixture()).api
+        self.placement_fixture = self.useFixture(
+            func_fixtures.PlacementFixture())
+        self.placement = self.placement_fixture.api
         self.neutron = self.useFixture(nova_fixtures.NeutronFixture(self))
         self.cinder = self.useFixture(nova_fixtures.CinderFixture(self))
         self.glance = self.useFixture(nova_fixtures.GlanceFixture(self))

nova/tests/functional/libvirt/test_pci_in_placement.py

@@ -87,6 +87,14 @@ class PlacementPCIReportingTests(test_pci_sriov_servers._PCIServersTestBase):
 
     def setUp(self):
         super().setUp()
+        # Use tuned placement config to exercise the more complex code
+        # path when pci_in_placement is used
+        self.placement_fixture.conf_fixture.config(
+                group='workarounds', optimize_for_wide_provider_trees=True)
+        self.placement_fixture.conf_fixture.config(
+                group='placement',
+                allocation_candidates_generation_strategy="breadth-first")
+
         self.flags(group="pci", report_in_placement=True)
 
         # These tests should not depend on the host's sysfs